Method and system for mobile communication, and a computer product

ABSTRACT

A management server managing a fixed address of a mobile terminal, at least two dynamic addresses dynamically allotted to the mobile terminal when it exists in two service areas at one time. A host transmits a packet with the fixed address of the mobile terminal used as a header. If the mobile terminal exist in at least the two service areas (apart from other areas), it notifies a management server of the dynamic addresses of the two service areas in real time. If the packet is transmitted from the host and the two dynamic addresses are allotted to the mobile terminal, the management server transfers a packet with these two dynamic addresses used as a header.

FIELD OF THE INVENTION

[0001] The present invention in general relates to a technology appliedin mobile terminals such as portable telephones and portable informationequipments, or mobile communication control devices. This inventionparticularly relates to a technology which reduces the labor requiredfor network management and control load relating to hand-over(switchover of containing radio base stations).

BACKGROUND OF THE INVENTION

[0002] In recent years, with the explosive spread of mobile terminals,network control and management tend to become increasingly complicated.During hand-over for smoothly switching over containing radio basestations following the area movement of a mobile terminal, particularly,it is necessary to make equipment on the network cooperate with oneanother. Due to this, the problem of network control and management loadappears. Means and methods for effectively solving this problem havebeen, therefore, demanded.

[0003]FIG. 9 is a block diagram that shows the constitution of aconventional mobile communication system. As shown in this figure, afixed telephone 1 is installed in, for example, a company or house andserves as a terminal establishing voice-communication with a mobileterminal 10 to be described later or other fixed telephones through anexternal network 2. A switchboard 3 is contained in the external network2 and switches over calls. A management server 4 manages positionalinformation indicating the position (area) at which the mobile terminal10 is present. A region main switchboard 5 is contained in a mobilecommunication network 6 and switches over calls.

[0004] A switchboard 7 ₁ is contained in the mobile communicationnetwork 6 and switches over mobile communicationcalls. This switchboard7 ₁ contains radio base stations 8 ₁ and 8 ₂. The radio base station 8 ₁establishes communication with the mobile terminal within an area 9 ₁through a radio line. The radio base station 8 ₂ establishescommunication with a mobile terminal within an area 9 ₂ adjacent thearea 9 ₁ through a radio line.

[0005] A switchboard 7 ₂ is contained in the mobile communicationnetwork 6 and switches over mobile communication calls. This switchboard7 ₂ contains radio base stations 8 ₃ and 8 ₄. The radio base station 8 ₃establishes communication with the mobile terminal within an area 9 ₃adjacent the area 9 ₂ through a radio line. The radio base station 8 ₄establishes communication with the mobile terminal within an area 9 ₄adjacent the area 9 ₃ through a radio line.

[0006] The mobile terminal 10 is a portable telephone or the like andestablishes radio-communication with any one of the radio base stations8 ₁ to 8 ₄ if the terminal 10 is located in any one of the areas 9 ₁ to9 ₄. The mobile terminal 10 regularly informs the management server 4 ofpositional information. Here, in the areas 9 ₁ to 9 ₄ stated above, amulti-area method by which adjacent two areas are set to overlap eachother is adopted. In the overlapping areas, therefore, the mobileterminal 10 informs the management server 4 of information on twopositions.

[0007] With the above constitution, when the fixed telephone 1 calls themobile terminal 10, the call from the fixed telephone 1 reaches theswitchboard 3 through the external network 2. Accordingly, theswitchboard 3 accesses the management server 4 and acquires positionalinformation on the mobile terminal 10. In this case, it is assumed thatthe mobile terminal 10 is located in the area 9 ₁. Next, the switchboard3 switches over the call to the regional main switchboard 5.Accordingly, a wire line is set in the route of the mobile communicationnetwork 6, the switchboard 7 ₁ and the radio base station 8 ₁ andfurther the mobile terminal 10 in the area 9 ₁ is called by the radiobase station 8 ₁ through the radio line. When the mobile terminal 10responds to the call, a line is established between the fixed telephone1 and the mobile terminal 10.

[0008] Assumed that the mobile terminal 10 is moving from the area 9 ₁to the area 9 ₂ while the communication line is being established.Namely, the mobile terminal 10 is located in a portion in which theareas 9 ₁ and 9 ₂ overlap each other. Therefore, the mobile terminal 10informs the management server 4 of not only positional informationcorresponding to the area 9 ₁ but also that corresponding to the area 9₂ through the radio base station 8 ₂, the switchboard 7 ₁, the mobilecommunication network 6 and the regional main switchboard 5.

[0009] Here, if a reception field intensity corresponding to the radiobase station 8 ₂ exceeds that corresponding to the radio base station 8₁, the mobile terminal 10 informs the radio base station 8 ₂ of aswitchover request for switching over the containing radio base stationfrom the radio base station 8 ₁ to the radio base station 8 ₂. Followingthis, the radio base station 8 ₂ informs the management server 4 of theswitchover request by way of the switchboard 7 ₁, the mobilecommunication network 6 and the regional main switchboard 5.

[0010] The management server 4 notifies the switchboard 7 ₁ that thecontaining radio base station of the mobile terminal 10 should beswitched over from the radio base station 8 ₁ to the radio base station8 ₂. By doing so, information necessary for line control is transmittedfrom the radio base station 8 ₁ to the radio base station 8 ₂ throughthe switchboard 7 ₁. When receiving the information, the radio basestation 8 ₂ establishes a radio line with the mobile terminal 10 in thearea 9 ₂. Next, the radio base station 8 ₁ disconnects the radio linewith the mobile terminal 10. In this way, the mutual cooperation amongthe switchboard 7 ₁, the radio base station 8 ₁, the radio base station8 ₂ and the management server 4 conventionally allows smooth switchover(hand-over) from the radio base station 8 ₁ to the radio base station 8₂.

[0011] In the meantime, as already described above, during hand-over inmobile communications, control and management are required to make aplurality of equipment (the radio base station 8 ₁, the switchboard 7 ₁,the management server 4 and the like) at the wire network side cooperatewith one another. However, during the hand-over, since it is necessaryto communicate information among the equipment and to conduct complexcontrol, great network management and control load is generated.Particularly, in circumstances where the number of operating mobileterminals increases rapidly, the network management and control loadincreases steadily, accordingly.

SUMMARY OF THE INVENTION

[0012] It is an object of the present invention to provide a method andsystem for mobile communication which reduces a work load of networkcontrol and management during hand-over. It is another object of thisinvention to provide a computer readable recording medium that stores acomputer program which when executed realizes the method according tothe present invention.

[0013] The mobile communication system according to the presentinvention comprises a management server which manages a fixed address ofthe mobile terminal and not less than one dynamic address dynamicallyallotted to the mobile terminal within not less than one service areaand a host transmitting information with the fixed address used as aheader. The mobile terminal notifies the management server of thedynamic address in a real time manner, and notifies, if stretching overat least two service areas, the management server of a first dynamicaddress and a second dynamic address corresponding to the at least twoservice areas. The management server transfers the information with thefirst dynamic address and the second dynamic address used as a header ifthe information is transmitted from the host and the first dynamicaddress and the second dynamic address are allotted to the mobileterminal.

[0014] Thus, if one or more dynamic addresses of the mobile terminal aremanaged unitarily by the management server in a real time manner,information is transmitted from the host and one or more dynamicaddresses are allotted to the mobile terminal, then information istransferred while using the one or more dynamic addresses allotted atthis moment as a header. Therefore, compared with a conventional case,it is possible to reduce network control and management load relating tohand-over.

[0015] Furthermore, if the mobile terminal stretches over at least twoservice areas, information is transferred while using the first dynamicaddress and the second dynamic address corresponding to the respectiveservice areas as a header. It is, therefore, possible to considerablydecrease the probability of momentary disconnection during hand-over.

[0016] Other objects and features of this invention will become apparentfrom the following description with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a block diagram showing the constitution of oneembodiment according to the present invention;

[0018]FIG. 2A to FIG. 2D show dynamic address management tables 100,110, 120 and 130;

[0019]FIG. 3A to FIG. 3C show dynamic address addition list packets 200,210 and a dynamic address deletion list packet 220;

[0020]FIG. 4A to FIG. 4C show transfer start request packets 300, 310and a transfer stop request packet 320;

[0021]FIG. 5A to FIG. 5C show transfer status tables 400, 410 and 420;

[0022]FIG. 6A to FIG. 6C show shortened route dynamic addressnotification packets 500, 510 and 520;

[0023]FIG. 7A to FIG. 7C show shortened route dynamic address tables600, 610 and 620;

[0024]FIG. 8 is a block diagram showing a modification of the embodimentshown in FIG. 1, and

[0025]FIG. 9 is a block diagram showing the constitution of aconventional mobile communication system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] A preferred embodiment according to the present invention and itsmodification will be explained below with reference to the attacheddrawings.

[0027]FIG. 1 is a block diagram showing the constitution of oneembodiment according to the present invention. As shown in this figure,a host 11 is connected to an external network 12 and transmits packetsto the fixed address MA of a mobile terminal 22 to be described later.This external network 12 is connected to a main network 13. A fixednetwork 14 is connected to the main network 13. The mobile terminal 22to be described later is connected to the fixed network 14. In FIG. 1,the mobile terminal 22 is separated from the fixed network 14. The fixedaddress MA is allotted, as an IP address, to the mobile terminal 22 tobe connected to the fixed network 14.

[0028] A management server 15 manages the fixed address MA of the mobileterminal 22, dynamic addresses MA1, MA2 and the like to be describedlater. A router 16 is interposed between the main network 13 and amobile communication main network 17, and routes packets. A router 18 ₁is interposed between the mobile communication main network 17 and abranch network 19 ₁ and routes packets. This branch network 19 ₁contains radio base stations 20 ₁ and 20 ₂. The radio base station 20 ₁communicates with the mobile terminal within an area 21 ₁ through aradio line. On the other hand, the radio base station 20 ₂ communicateswith the mobile terminal within an area 21 ₂ adjacent the area 21 ₂.

[0029] A router 18 ₂ is interposed between the mobile communication mainnetwork 17 and a branch network 19 ₂ and routes packets. This branchnetwork 19 ₂ contains radio base stations 20 ₃ and 20 ₄. The radio basestation 20 ₃ communicates with the mobile terminal within an area 21 ₃through a radio line. The radio base station 20 ₄ communicates with themobile terminal within an area 21 ₄ adjacent the area 21 ₃ through aradio line.

[0030] The mobile terminal 22 is a portable information terminal or thelike and establishes radio-communication with one of or a plurality ofthe radio base stations 20 ₁ to 20 ₄ if the terminal 22 is located inany one of the areas 21 ₁ to 21 ₄. Also, dynamic addresses are allottedto the mobile terminal 22 for the respective areas. If the mobileterminal 22 is located in the area 21 ₁, for example, a dynamic addressMA1 is allotted to the mobile terminal 22. If the mobile terminal 22 islocated in the area 21 ₂, a dynamic addresses MA2 is allotted to themobile terminal 22. Here, in the above-stated areas 21 ₁ to 21 ₄, amultiple area mode by which adjacent two areas are set to overlap eachother is adopted. In overlapping areas, therefore, two dynamic addressesare allotted to the mobile terminal 22.

OPERATION EXAMPLE 1

[0031] Next, an operation example 1 of the present invention will bedescribed while referring to FIG. 1. When the mobile terminal 22 entersthe area 21 ₁, the dynamic address MA1 is allotted to the mobileterminal 22. The mobile terminal 22 transmits a dynamic address additionlist packet 200 shown in FIG. 3A to the management server 15,accordingly.

[0032] The dynamic address addition list packet 200 is a packet forrequesting the management server 15 to add the dynamic address MA1 to a“dynamic address” field on a dynamic address management table 100 shownin FIG. 2A. The dynamic address list packet 200 is received by themanagement server 15 by way of the radio base station 20 ₁, the branchnetwork 19 ₁, the router 18 ₁, the mobile communication main network 17,the router 16, the main network 13 and the fixed network 14.

[0033] The management server 15 adds the dynamic address MA1 (see FIG.3A) within the dynamic address addition list packet 200 to the “dynamicaddress” field on the dynamic address management table 100 (see FIG. 2A)which field corresponds to the mobile terminal 22, as shown in FIG. 2B.Thus, the dynamic address table 100 becomes a dynamic address managementtable 110. During this state, if a packet is transmitted from the host11 to the mobile terminal 22, the host 11 transmits a packet with thefixed address MA of the mobile terminal 22 used as a header. As aresult, the packet is transmitted to the fixed address MA by way of theexternal network 12, the main network 13 and the fixed network 14.

[0034] However, since the mobile terminal 22 is not connected to thefixed network 14, the management server 15 receives the above-statedpacket in place of the mobile terminal 22. Next, the management server15 refers to the dynamic address management table 110 shown in FIG. 2Band transmits the packet with the dynamic address MA1 allotted to themobile terminal 22 used as a new header. By doing so, the packet isreceived by the mobile terminal 22 within the area 21 ₁ by way of thefixed network 14, the main network 13, the router 16, the mobilecommunication main network 17, the router 18 ₁, the branch network 19 ₁and the radio base station 20 ₁.

[0035] During this state, if the mobile terminal 22 moves to an area inwhich the areas 21 ₁ and 21 ₂ overlap each other, a dynamic address MA2as well as the dynamic address MA1 is allotted to the mobile terminal22. The mobile terminal 22 transmits a dynamic address addition listpacket 210 shown in FIG. 3B to the management server 15, accordingly.

[0036] This dynamic address addition list packet 210 is a packet forrequesting the management server 15 to add the dynamic address MA2 tothe “dynamic address” field on the dynamic address management table 110shown in FIG. 2B. The dynamic address addition list packet 210 isreceived by the management server 15 by way of the radio base station 20₁, the branch network 19 ₁, the router 18, the mobile communication mainnetwork 17, the router 16, the main network 13 and the fixed network 14.

[0037] The management server 15 adds the dynamic address MA2 (see FIG.3B) within the dynamic address addition list packet 210 to the “dynamicaddress field” on the dynamic address management table 110 (see FIG. 2B)which field corresponds to the mobile terminal 22 as shown in FIG. 2C.Thus, the dynamic address management table 11 becomes a dynamic addressmanagement table 120.

[0038] In this case, the management server 15 refers to the dynamicaddress management table 120 shown in FIG. 2C and outputs a packet withthe dynamic addresses MA1 and MA2 currently allotted to the mobileterminal 22 used as a new header. By doing so, the packet is received bythe router 18, by way of the router 16 and the mobile communication mainnetwork 17. The router 18 ₁ refers to the header (the dynamic addressesMA1 and MA2) of the packet, duplicates the packet and routes the packetsto both the radio base stations 20 ₁ and 20 ₂. As a result, the packetis received by the mobile terminal 22 within the areas 21 ₁ and 21 ₂.

[0039] During this state, if the mobile terminal 22 goes out of the area21 ₁ and exists only in the area 21 ₂, the allotment of the dynamicaddress MA1 to themobile terminal 22 is released and only the dynamicaddress MA2 is allotted to the mobile terminal 22. Thus, the mobileterminal 22 transmits the dynamic address deletion list packet 220 shownin FIG. 3C to the management server 15.

[0040] This dynamic address deletion list packet 220 is a packet forrequesting the management server 15 to delete the dynamic address MA1from the “dynamic address” field on the dynamic address management table120 shown in FIG. 2C. The dynamic address deletion list packet 220 isreceived by the management server 15 by way of the radio base station 20₂, the branch network 19 ₁,the router 18 ₁, the mobile communicationmain network 17, the router 16, the main network 13 and the fixednetwork 14.

[0041] The management server 15 deletes the dynamic address MA1 (seeFIG. 3C) from the “dynamic address” field on the dynamic addressmanagement table 120 (see FIG. 2C) which field corresponds to the mobileterminal 22 as shown in FIG. 2D. Thus, the dynamic address managementtable 120 becomes a dynamic address management table 130.

[0042] In this case, the management server 15 refers to the dynamicaddress management table 130 shown in FIG. 2D and transmits a packetwith the dynamic address MA2 currently allotted to the mobile terminal22 used as a new header. By doing so, the packet is received by themobile terminal 22 within the area 21 ₂ by way of the router 16, themobile communication main network 17, the router 18 ₁, the branchnetwork 19 ₁ and the radio base station 20 ₂.

OPERATION EXAMPLE 2

[0043] Next, an operation example 2 of the present invention will bedescribed while referring to FIG. 1. When the mobile terminal 22 entersthe area 21 ₁, the dynamic address MA1 is allotted to the mobileterminal 22. The mobile terminal 22 transmits the dynamic addressaddition list packet 200 shown in FIG. 3A to the management server 15,accordingly. As a result, as in the case of the operation example 1described above, the dynamic address addition list packet 200 isreceived by the management server 15.

[0044] The management server 15 adds the dynamic address MA1 (see FIG.3A) within the dynamic address addition list packet 200 to the “dynamicaddress field” on the dynamic address management table 100 (see FIG. 2A)which field corresponds to the mobile terminal 22 as shown in FIG. 2B.Thus, the dynamic address management table 100 becomes the dynamicaddress management table 110.

[0045] Further, simultaneously with the transmission of the dynamicaddress addition list packet 200, the mobile terminal 22 transmits atransfer start request packet 300 shown in FIG. 4A to the radio basestation 20 ₁. This transfer start request packet 300 is a packet forrequesting the radio base station 20 ₁ to start transferring a packetaddressed to the mobile terminal 22 (or the dynamic address MA1 in thiscase).

[0046] When receiving the transfer start request packet 300, the radiobase station 20 ₁ creates a transfer status table 400 shown in FIG. 5Abased on the transfer start request packet 300. This transfer statustable 400 is comprised of a “dynamic address” field indicating a dynamicaddress to which a packet is transferred, and a “transfer status” fieldindicating whether to start or stop transfer. In the example shown inFIG. 5A, it is assumed that “dynamic address”=“dynamic address MA1” and“transfer status”=“start”.

[0047] During this state, if a packet is transmitted from the host 11 tothe mobile terminal 22, the host 11 transmits a packet with the fixedaddress MA of the mobile terminal 22 used as a header. By doing so, thepacket is transmitted to the fixed address MA by way of the externalnetwork 12, the main network 13 and the fixed network 14.

[0048] However, since the mobile terminal 22 is not connected to thefixed network 14, the management server 15 refers to the dynamic addressmanagement table 110 shown in FIG. 2B and transmits the above-statedpacket with the dynamic address MA1 allotted to the mobile terminal 22used as a new header as in the case of the operation example 1 alreadydescribed above. As a result, the packet is received by the radio basestation 20 ₁ by way of the fixed network 14, the main network 13, therouter 16, the mobile communication main network 17, the router 18 ₁ andthe branch network 19 ₁.

[0049] The radio base station 20 ₁ refers to the transfer status table400 shown in FIG. 5A using the header (dynamic address MA1) of thereceived packet as a key, and recognizes that the “transfer status”relating to the dynamic address is “start”. In this case, the radio basestation 20 ₁ transfers the packet to the dynamic address MA1. By doingso, the packet is received by the mobile terminal 22 through the radioline.

[0050] During this state, if the mobile terminal 22 moves to an area inwhich the areas 21 ₁ and 21 ₂ overlap each other, the dynamic addressMA2 as well as the dynamic address MA1 is allotted to the mobileterminal 22. Thus, as in the case of the operation example 1, the mobileterminal 22 transmits the dynamic address addition list packet 210 shownin FIG. 3B to the management server 15. This dynamic address additionlist packet 210 is received by the management server 15 by way of theradio base station 20 ₂, the branch network 19 ₁, the router 18 ₁, themobile communication main network 17, the router 16, the main network 13and the fixed network 14.

[0051] The management server 15 adds the dynamic address MA2 (see FIG.3B) within the dynamic address addition list packet 210 to the “dynamicaddress” field on the dynamic address management table 110 (see FIG. 2B)which field corresponds to the mobile terminal 22 as shown in FIG. 2C.Thus, the dynamic address management table 110 becomes the dynamicaddress management table 120.

[0052] In this case, as in the case of the operation example 1, themanagement server 15 outputs a packet with the dynamic addresses MA1 andMA2 currently allotted to the mobile terminal 22 used as a new header.By doing so, the packet is received by the router 18 ₁ by way of thefixed network 14, the main network 13, the router 16 and the mobilecommunication main network 17. The router 18 ₁ refers to the header(dynamic addresses MA1 and MA2) of the packet, duplicates the packetsand routes these packets to both the radio base stations 20 ₁ and 20 ₂.

[0053] Then, the radio base station 20 ₁ refers to the transfer statustable 400 (see FIG. 5A) and transfers the above-stated packet to thedynamic address MA1 (or the mobile terminal 22) through the radio line.The radio base station 20 ₂, which does not receives the transfer startrequest packet from the mobile terminal 22, destroys the packet and doesnot transfer the packet to the dynamic address MA2 (or the mobileterminal 22). In this case, therefore, the mobile terminal 22 receivesthe packet from the radio base station 20 ₁.

[0054] Here, if a reception field intensity corresponding to the radiobase station 20 ₂ exceeds that corresponding to the radio base station20 ₁, the mobile terminal 22 transmits a transfer start request packet310 shown in FIG. 4B to the radio base station 20 ₂. This transfer startrequest packet 310 is a packet for requesting the radio base station 20₂ to start transferring the packet addressed to the mobile terminal 22(or the dynamic address MA2 in this case).

[0055] When receiving the transfer start request packet, the radio basestation 20 ₂ creates a transfer status table 410 shown in FIG. 5B basedon the transfer start request packet 310. This transfer status table 410is comprised of a “dynamic address” field indicating a dynamic addressto which a packet is transferred and a “transfer status” fieldindicating whether to start or stop transfer. In the example shown inFIG. 5B, it is assumed that “dynamic address”=“dynamic address MA2” and“transfer status”=“start”.

[0056] Next, the mobile terminal 22 transmits a transfer stop requestpacket 320 shown in FIG. 4C to the radio base station 20 ₁. Thistransfer stop request packet 320 is a packet for requesting the radiobase station 20 ₁ to stop transferring the packet to the mobile terminal22 (or the dynamic address MA1 in this case).

[0057] When receiving the transfer stop request packet, the radio basestation 20 ₁ changes the “transfer status” on the transfer status tableshown in FIG. 5A from “start” to “stop” based on the transfer stoprequest packet 320. As a result, the transfer status table 400 becomes atransfer status table 420 shown in FIG. 5C.

[0058] Then, the radio base station 20 ₂ refers to a transfer statustable 410 (see FIG. 5B) and transfers the packet to the dynamic addressMA2 (or the mobile terminal 22) through the radio line. Thereafter, theradio base station 20 ₁ refers to a transfer status table 420 (see FIG.5C) and stops transferring the packet to the dynamic address MA1 (or themobile terminal 22). In this case, therefore, the mobile terminal 22receives the packet from the radio base station 20 ₂. As can be seen, inthe operation example 2, even while the area 21 ₁ is switched to thearea 21 ₂, communication is not momentarily stopped.

[0059] During this state, if the mobile terminal 22 goes out of the area21 ₁ and exists only in the area 21 ₂, the allotment of the dynamicaddress MA1 to the mobile terminal 22 is released and the mobileterminal 22 is allotted only the dynamic address MA2. Due to this, themobile terminal 22 transmits the dynamic address deletion list packet220 shown in FIG. 3C to the management server 15.

[0060] This dynamic address deletion list packet 220 is a packet forrequesting the management server 15 to delete the dynamic address MA1from the “dynamic address” field on the dynamic address management tableshown in FIG. 2C. The dynamic address deletion list packet 220 isreceived by the management server 15 by way of the radio base station 20₂, the branch network 19 ₁, the router 18 ₁, the mobile communicationmain network 17, the router 16, the main network 13 and the fixednetwork 14.

[0061] The management server 15 deletes the dynamic address MA1 (seeFIG. 3C) from the “dynamic address” field on the dynamic addressmanagement table 120 (see FIG. 2C) which field corresponds to the mobileterminal 22 as shown in FIG. 2D. Thus, the dynamic address managementtable 120 becomes the dynamic address management table 130.

[0062] In this case, the management server 15 refers to the dynamicaddress table 130 shown in FIG. 2D, and outputs a packet with thedynamic address MA2 currently allotted to the mobile terminal 22 used asa new header. By doing so, the packet is received by the radio basestation 20 ₂ by way of the fixed network 14, the main network 13, therouter 16, the mobile communication main network 17, the router 18 ₁ andthe branch network 19 ₁. Finally, the packet is retransmitted to themobile terminal 22 (to the dynamic address MA2) by the radio basesection 20 ₂.

OPERATION EXAMPLE 3

[0063] Next, an operation example 3 of the present invention will bedescribed while referring to FIG. 1. When the mobile terminal 22 entersthe area 21 ₁, the dynamic address MA1 is allotted to the mobileterminal 22. The mobile terminal 22 transmits the dynamic addressaddition list packet 200 shown in FIG. 3A to the management server 15,accordingly. As a result, the dynamic address addition list packet 200is received by the management server 15 by way of the radio base station20 ₁, the branch network 19 ₁, the router 18 ₁, the mobile communicationmain network 17, the router 16, the main network 13 and the fixednetwork 14 as in the case of the operation example 1.

[0064] The management server 15 adds the dynamic address MA1 (see FIG.3A) within the dynamic address addition list packet 200 to the “dynamicaddress” field on the dynamic address management table 100 (see FIG. 2Awhich field corresponds to the mobile terminal 22 as shown in FIG. 2B.Thus, the dynamic address management table 100 becomes the dynamicaddress management table 110. During this state, if a packet istransmitted from the host 11 with the fixed address MA of the mobileterminal 22 used as a header, this packet is transmitted to the fixedaddress MA by way of the external network 12, the main network 13 andthe fixed network 14.

[0065] However, since the mobile terminal 22 is not connected to thefixed network 14, the management server 15 refers to the dynamic addressmanagement table shown in FIG. 2B and outputs a packet with the dynamicaddress MA1 allotted to the mobile terminal 22 used as a header as inthe case of the operation example 1. As a result, the packet is receivedby the mobile terminal 22 within the area 21 ₁ by way of the fixednetwork 14, the main network 13, the router 16, the mobile communicationmain network 17, the router 18 ₁, the branch network 19 ₁ and the radiobase station 20 ₁.

[0066] Further, the management server 15 outputs a shortened routedynamic address notification packet 500 shown in FIG. 6A to the host 11after outputting the packet. This shortened route dynamic addressnotification packet 500 is a packet for notifying the dynamic addressMA1 for shortening a packet route from the host 11 to the mobileterminal 22.

[0067] That is to say, the packet transmitted from the host 11 istransferred to the mobile terminal 22 through the management server 15.In this case, therefore, the packet route becomes longer by a degree towhich the packet goes through the management server 15. In the operationexample 3, therefore, the shortened route dynamic address notificationpacket 500 is employed so as to directly transmit the packet to themobile terminal 22 allotted the dynamic address without going throughthe management server 15.

[0068] The shortened route dynamic address notification packet 500 isreceived by the host 11 by way of the fixed network 14, the main network13 and the external network 12. The host 11 creates a shortened routerdynamic address table 600 shown in FIG. 7A based on the shortened routedynamic address notification package 500. This shortened route dynamicaddress table 600 is comprised of a “mobile terminal” field, a “fixedaddress” field and a “route shortening dynamic address” field. In theexample shown in FIG. 7A, it is assumed that “mobile terminal”=mobileterminal 22, “fixed address”=MA and “route shortening dynamicaddress”=MA1.

[0069] The host 11 refers to the shortened route dynamic address table600 and changes the current header of the packet addressed to the mobileterminal 22 from “fixed address MA” to “dynamic address MA1”. By doingso, the host 11 transmits a packet with the dynamic address MA1 used asa header. This packet is directly received by the mobile terminal 22 byway of the external network 12, the main network 13, the router 16, themobile communication main network 17, the router 18 ₁, the branchnetwork 19 ₁ and the radio base station 20 ₁ without going through themanagement server 15.

[0070] During this state, if the mobile terminal 22 moves to an area inwhich the areas 21 ₁ and 21 ₂ overlap each other, the dynamic addressMA2 as well as the dynamic address MA1 is allotted to the mobileterminal 22. The mobile terminal 22 transmits the dynamic addressaddition list packet 210 shown in FIG. 3B to the management server 15,accordingly. This dynamic address addition list packet 210 is receivedby the management server 15 by way of the radio base station 20 ₁, thebranch network 19 ₁, the router 18 ₁, the mobile communication mainnetwork 17, the router 16, the main network 13 and the fixed network 14as in the case of the operation example 1.

[0071] The management server 15 adds the dynamic address MA2 (see FIG.3B) within the dynamic address addition list packet 210 to the “dynamicaddress” field on the dynamic address management table (see FIG. 2B)which field corresponds to the mobile terminal 22 as shown in FIG. 2C.Thus, the dynamic address management table 110 become the dynamicaddress management table 120.

[0072] In this case, the management table 15 refers to the dynamicaddress management table 120 shown in FIG. 2C, and outputs a packet withthe dynamic addresses MA1 and MA2 currently allotted to the mobileterminal 22 used as a new header. By doing so, the packet is received bythe router 18 ₁ by way of the fixed network 14, the main network 13, therouter 16 and the mobile communication main network 17. The router 18 ₁refers to the header (or the dynamic addresses MA1 and MA2) of thepacket, duplicates the packet and routes these packets to both the radiobase stations 20 ₁ and 20 ₂. As a result, the packet is received by themobile terminal 22 within the areas 21 ₁ and 21 ₂.

[0073] Further, the management server 15 outputs a shortened routedynamic address notification packet 510 shown in FIG. 6B to the host 11.This shortened route dynamic address notification packet 510 is a packetfor notifying the dynamic addresses MA1 and MA2 for shortening a packetroute from the host 11 to the mobile terminal 22.

[0074] The shortened route dynamic address notification packet 510 isreceived by the host 11 by way of the fixed network 14, the main network13 and the external network 12. The host 11 updates the “routeshortening dynamic address” on the shortened route dynamic address table600 shown in FIG. 7A to the dynamic addresses MA1 and MA2 based on theshortened route dynamic address notification packet 510. Thus, theshortened route dynamic address table 600 becomes the shortened routedynamic address table 610 shown in FIG. 7B.

[0075] The host 11 refers to the shortened route dynamic address table610 and changes the current header of the packet addressed to the mobileterminal 22 from “dynamic address MA1” to “dynamic addresses MA1 andMA2”. By doing so, the host 11 transmits a packet with the dynamicaddresses MA1 and MA2 used as a header. This packet is directly receivedby the mobile terminal 22 within the areas 21 ₁ and 21 ₂ by way of theexternal network 12, the main network 13, the router 16, the mobilecommunication main network 17, the router 18 ₁, the branch network 19 ₁,the radio base stations 20 ₁ and 20 ₂ without going through themanagement server 15.

[0076] During this state, if the mobile terminal 22 goes out of the area21 ₁ and exists only in the area 21 ₂, the allotment of the dynamicaddress MA1 to the mobile terminal 22 is released and the mobileterminal 22 is allotted only the dynamic address MA2. Thus, the mobileterminal 22 transmits the dynamic address deletion list packet 220 shownin FIG. 3C to the management server 15. As a result, the dynamic addressdeletion list packet 220 is received by the management server 15 by wayof the radio base station 20 ₂, the branch network 19 ₁, the router 18₁, the mobile communication main network 17, the router 16, the mainnetwork 13 and the fixed network 14.

[0077] The management server 15 deletes the dynamic address MA1 (seeFIG. 3C) from the “dynamic address” field on the dynamic addressmanagement table 120 (see FIG. 2C) which field corresponds to the mobileterminal 22 as shown in FIG. 2D. Thus, the dynamic address managementtable 120 becomes the dynamic address management table 130.

[0078] Further, the management server 15 outputs the shortened routedynamic address notification packet 520 shown in FIG. 6C to the host 11.This shortened route dynamic address notification packet 520 is a packetfor notifying the dynamic address MA2 for shortening a packet route fromthe host 11 to the mobile terminal 22.

[0079] The shortened route dynamic address notification packet 520 isreceived by the host 11 by way of the fixed network 14, the main network13 and the external network 12. The host 11 updates the “routeshortening dynamic address” on the shortened route dynamic address table610 shown in FIG. 7B to the dynamic address MA2 based on the shortenedroute dynamic address notification packet 520. Thus, the shortened routedynamic address table 610 becomes the shortened route dynamic addresstable 620 shown in FIG. 7C.

[0080] The host 11 refers to the shortened route dynamic address table620 and changes the current header of the packet addressed to the mobileterminal 22 from “dynamic addresses MA1 and MA2” to “dynamic addressMA2”. By doing so, the host 11 transmits a packet with the dynamicaddress MA2 as a header. This packet is directly received by the mobileterminal 22 within the area 21 ₂ by way of the external network 12, themain network 13, the router 16, the mobile communication main network17, the router 18 ₁, the branch network 19 ₁ and the radio base station20 ₂ without going through the management server 15.

[0081] As stated so far, the dynamic address of the mobile terminal 22is managed unitarily by the management server 15 in a real time manner.If a packet is transmitted from the host 11 and a dynamic address isallotted to the mobile terminal 22, the packet is transferred while thedynamic address allotted at this moment is used as a header. Therefore,compared with a conventional case, it is possible to reduce networkcontrol and management load relating to hand-over.

[0082] Furthermore, if the mobile terminal 22 stretches over two areas(e.g., areas 21 ₁ and 21 ₂), a packet is transferred while two dynamicaddresses (e.g., dynamic addresses MA1 and MA2) corresponding to therespective areas is used as a header. Thus, it is possible toconsiderably decrease the probability of momentary disconnection duringthe hand-over.

[0083] Moreover, during hand-over, after packet transfer start isrequested to the radio base station 20 ₂ covering one area (e.g., area21 ₂), packet transfer stop is requested to the radio base station 20 ₁covering the other area (e.g., area 21 ₁). It is, therefore, possible toreduce unnecessary traffic among radio lines.

[0084] In addition, the host 11 is notified of the dynamic address fromthe management server 15 in a real time manner and the host 11 directlytransmits a packet with this dynamic address instead of the fixedaddress used as a header. It is, therefore, possible to shorten a packettransmission route.

[0085] One embodiment of the present invention has been described indetail with reference to the drawings. It is noted, however, that theconcrete examples of the constitution of the invention should not belimited to this embodiment and that any changes in design or the likewithin the scope of the present invention are included in the presentinvention. For example, in the embodiment stated above, communicationcontrol may be conducted by recording a mobile communication controlprogram for realizing the function of the management server 15 on acomputer readable recording medium 900 shown in FIG. 8, allowing acomputer shown in FIG. 8 to read and execute the mobile communicationcontrol program recorded on this recording medium 900.

[0086] The computer 800 shown in FIG. 8 consists of a CPU 801 executingthe mobile communication control program, an input device 802 includinga keyboard, a mouse and the like, an ROM (Read OnlyMemory) 803 storingvarious data, an RAM (Random Access Memory) 804 storing operationparameters and the like, a reader 805 reading the mobile communicationcontrol program from the recording medium 900, an output device 806including a display, a printer and the like, and a bus BU connecting therespective constituent elements.

[0087] The CPU 801 reads the mobile communication control programrecorded on the recording medium 900 through the reader 805 and thenexecutes the mobile communication control program, thereby conductingcommunication control as described above. The recording medium 900includes not only portable recording mediums such as an optical disk, afloppy disk and a hard disk but also transmission mediums, such as anetwork, for temporarily recording and storing data.

[0088] The host 11 may be notified of the dynamic address from themobile terminal 22 in a real time manner and the host 11 may transmit apacket with this dynamic address instead of the fixed address used as aheader. If so, it is possible to further shorten a packet transmissionroute.

[0089] Further, according to one embodiment, description has been givento a case of realizing hand-over by transferring packets to the mobileterminal 22 from two radio base stations 20 ₁ and 20 ₂ if the mobileterminal 22 stretches over two areas 21 ₁ and 21 ₂. If the mobileterminal 22 stretches over three or more areas, it is possible torealize hand-over by transferring packets to the mobile terminal 22 fromtwo ore more (or three or more) base stations.

[0090] Thus, according to the present invention, if one or more dynamicaddresses of the mobile terminal are managed unitarily by the managementserver in a real time manner, information is transmitted from the hostand one or more dynamic addresses are allotted to the mobile terminal,then information is transferred while using the one or more dynamicaddresses allotted at this moment as a header. Therefore, compared witha conventional case, it is possible to advantageously reduce networkcontrol and management load relating to hand-over.

[0091] Furthermore, if the mobile terminal stretches over at least twoservice areas, information is transferred while using the first dynamicaddress and the second dynamic address corresponding to the respectiveservice areas as a header. It is, therefore, possible to advantageously,considerably decrease the probability of momentary disconnection duringhand-over.

[0092] Moreover, during the hand-over, after information transfer startis requested to a radio base station covering one area, informationtransfer stop is requested to a radio base station covering the otherarea. It is, therefore, possible to advantageously reduce unnecessarytraffic among radio lines.

[0093] In addition, the host is notified of the dynamic address from themanagement server in a real time manner and the host directly transmitsinformation with this dynamic address instead of the fixed address usedas a header. It is, therefore, possible to advantageously shorten apacket transmission route.

[0094] Furthermore, the host is notified of the dynamic address from themobile terminal in a real time manner and the host transmits informationwith this dynamic address instead of the fixed address used as a header.It is, therefore, possible to advantageously, further shorten the packettransmission route.

[0095] Furthermore, if a plurality of dynamic addresses of the mobileterminal are managed unitarily by the management server in a real timemanner, information is transmitted from the host and a plurality ofdynamic addresses are allotted to the mobile terminal, then informationis transferred while using the plurality of dynamic addresses allottedat this moment as a header. Therefore, compared with a conventionalcase, it is possible to advantageously reduce network control andmanagement load relating to hand-over.

[0096] Although the invention has been described with respect to aspecific embodiment for a complete and clear disclosure, the appendedclaims are not to be thus limited but are to be construed as embodyingall modifications and alternative constructions that may occur to oneskilled in the art which fairly fall within the basic teaching hereinset forth.

What is claimed is:
 1. A mobile communication system comprising: a host;a plurality of radio base stations, each of said plurality of radio basestations covering a service area; at least one mobile terminal, whereinsaid least one mobile terminal and said host perform communication witheach other through a base station out of said plurality of radio basestations in whose service area said least one mobile terminal ispresent; and a management server which manages a) a fixed address ofsaid least one mobile terminal, and b) at least two dynamic addressdynamically allotted to said least one mobile terminal when it is inmany service areas at one time, wherein said host transmits informationwith the fixed address of said least one mobile terminal as a header,said least one mobile terminal notifies said management server of thedynamic address in a real time manner, and notifies, if stretching overat least two service areas, said management server of a first dynamicaddress and a second dynamic address corresponding to the at least twoservice areas, and said management server transfers the information withthe first dynamic address and the second dynamic address used as aheader if the information is transmitted from said host and the firstdynamic address and the second dynamic address are allotted to saidleast one mobile terminal.
 2. The mobile communication system accordingto claim 1, wherein each of said plurality of radio base stations startstransferring information based on the dynamic address of said least onemobile terminal when receiving an information transfer start requestfrom said least one mobile terminal, and stops transferring theinformation to said least one mobile terminal when receiving aninformation transfer stop request from said least one mobile terminal,and during hand-over, said least one mobile terminal makes theinformation transfer start request to one of said radio base stationscovering one of said service areas and thereafter makes the informationtransfer stop request to one of said radio base stations covering theother service area.
 3. The mobile communication system according toclaim 1, wherein said management server notifies said host of thedynamic address in a real time manner, and if the dynamic address isallotted to said least one mobile terminal, said host transmits theinformation with the dynamic address allotted at this moment used as aheader.
 4. The mobile communication system according to claim 1, whereinsaid least one mobile terminal notifies said host of the dynamic addressin a real time manner, and if notified, said host transmits theinformation with the dynamic address, instead of the fixed address, usedas a header.
 5. A mobile communication system comprising: a host; aplurality of radio base stations, each of said plurality of radio basestations covering a service area; at least one mobile terminal, whereinsaid least one mobile terminal and said host perform communication witheach other through a base station out of said plurality of radio basestations in whose service area said least one mobile terminal ispresent; and a management server which manages a) a fixed address ofsaid least one mobile terminal, and b) at least two dynamic addressdynamically allotted to said least one mobile terminal when it is in atmany service areas at one time, wherein said host transmits informationwith the fixed address of said least one mobile terminal as a header,when said least one mobile terminal stretches over a plurality ofservice areas it notifies said management server of a plurality ofdynamic addresses corresponding to the plurality of service areas, andwhen such information is transmitted from said host and the plurality ofdynamic addresses are allotted to said least one mobile terminal, saidmanagement server transfers the information with the plurality ofdynamic addresses used as a header.
 6. A mobile communication controlapparatus adapted to a mobile communication system, which mobilecommunication system having, a host; a plurality of radio base stations,each of said plurality of radio base stations covering a service area;and at least one mobile terminal, wherein said least one mobile terminaland said host perform communication with each other through a basestation out of said plurality of radio base stations in whose servicearea said least one mobile terminal is present, said mobilecommunication control apparatus comprising: a management unit whichmanages a) a fixed address of said least one mobile terminal, and, b) atleast two dynamic address dynamically allotted to said least one mobileterminal when it is in many service areas at one time and notified in areal time manner from said least one mobile terminal; and a transferunit which, if the information is transmitted from said host with thefixed address used as a header, said least one mobile terminal stretchesover at least two service areas and a first dynamic address and a seconddynamic address corresponding to the respective service areas areallotted to said least one mobile terminal, transfers the informationwith the first dynamic address and the second dynamic address used as aheader.
 7. A mobile communication control apparatus adapted to a mobilecommunication system, which mobile communication system having, a host;a plurality of radio base stations, each of said plurality of radio basestations covering a service area; and at least one mobile terminal,wherein said least one mobile terminal and said host performcommunication with each other through a base station out of saidplurality of radio base stations in whose service area said least onemobile terminal is present, said mobile communication control apparatuscomprising: a management unit which manages a) a fixed address of saidleast one mobile terminal, and, b) at least two dynamic addressdynamically allotted to said least one mobile terminal when it is inmany service areas at one time and notified in a real time manner fromsaid least one mobile terminal; and a transfer unit which, ifinformation is transmitted from said host with the fixed address used asa header, said least one mobile terminal stretches over a plurality ofservice areas and a plurality of dynamic addresses corresponding to therespective service areas, transfers the information with the pluralityof dynamic addresses used as a header.
 8. A mobile communication controlmethod adapted to a mobile communication system, which mobilecommunication system having, a host; a plurality of radio base stations,each of said plurality of radio base stations covering a service area;and at least one mobile terminal, wherein said least one mobile terminaland said host perform communication with each other through a basestation out of said plurality of radio base stations in whose servicearea said least one mobile terminal is present, the mobile communicationcontrol method comprising: a management step of managing a) a fixedaddress of said least one mobile terminal, and, b) at least two dynamicaddress dynamically allotted to said least one mobile terminal when itis in many service areas at one time and notified in a real time mannerfrom said least one mobile terminal; and a transfer step of, if theinformation is transmitted from said host with the fixed address used asa header, said least one mobile terminal stretches over at least twoservice areas and a first dynamic address and a second dynamic addresscorresponding to the respective service areas are allotted to said leastone mobile terminal, transferring the information with the first dynamicaddress and the second dynamic address used as a header.
 9. A mobilecommunication control method adapted to a mobile communication system,which mobile communication system having, a host; a plurality of radiobase stations, each of said plurality of radio base stations covering aservice area; and at least one mobile terminal, wherein said least onemobile terminal and said host perform communication with each otherthrough a base station out of said plurality of radio base stations inwhose service area said least one mobile terminal is present, the mobilecommunication control method comprising: a management step of managinga) a fixed address of said least one mobile terminal, and, b) at leasttwo dynamic address dynamically allotted to said least one mobileterminal when it is in many service areas at one time and notified in areal time manner from said least one mobile terminal; and a transferstep of, if information is transmitted from said host with the fixedaddress used as a header, said least one mobile terminal stretches overa plurality of service areas and a plurality of dynamic addressescorresponding to the respective service areas, transferring theinformation with the plurality of dynamic addresses used as a header.10. A computer readable medium for storing instructions, which whenexecuted by a computer, causes the computer to realize a mobilecommunication control method adapted to a mobile communication system,which mobile communication system having, a host; a plurality of radiobase stations, each of said plurality of radio base stations covering aservice area; and at least one mobile terminal, wherein said least onemobile terminal and said host perform communication with each otherthrough a base station out of said plurality of radio base stations inwhose service area said least one mobile terminal is present, the mobilecommunication control method comprising: a management step of managinga) a fixed address of said least one mobile terminal, and, b) at leasttwo dynamic address dynamically allotted to said least one mobileterminal when it is in many service areas at one time and notified in areal time manner from said least one mobile terminal; and a transferstep of, if the information is transmitted from said host with the fixedaddress used as a header, said least one mobile terminal stretches overat least two service areas and a first dynamic address and a seconddynamic address corresponding to the respective service areas areallotted to said least one mobile terminal, transferring the informationwith the first dynamic address and the second dynamic address used as aheader.
 11. A computer readable medium for storing instructions, whichwhen executed by a computer, causes the computer to realize a mobilecommunication control method adapted to a mobile communication system,which mobile communication system having, a host; a plurality of radiobase stations, each of said plurality of radio base stations covering aservice area; and at least one mobile terminal, wherein said least onemobile terminal and said host perform communication with each otherthrough a base station out of said plurality of radio base stations inwhose service area said least one mobile terminal is present, the mobilecommunication control method comprising: a management step of managinga) a fixed address of said least one mobile terminal, and, b) at leasttwo dynamic address dynamically allotted to said least one mobileterminal when it is in many service areas at one time and notified in areal time manner from said least one mobile terminal; and a transferstep of, if information is transmitted from said host with the fixedaddress used as a header, said least one mobile terminal stretches overa plurality of service areas and a plurality of dynamic addressescorresponding to the respective service areas, transferring theinformation with the plurality of dynamic addresses used as a header.